<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        html,body{
            width: 100%;
            height: 100%;
        }
        .box{
            height: 100%;
            width: 100%;
            column-count: 3;
            /* 列数 */
            column-gap: 60px;
            /* 间隙 */
            /* 列宽 */
            /* column-width: 100px; */
            /* column-rule-color: red;
            column-rule-width: 10px;
            column-rule-style: dashed; */
            column-rule: 10px dashed red;
        }
        .inner{
            border: 1px solid #000;
            height: 80%;
            box-sizing: border-box;
        }
        h1{
            /* 让标题横穿三列 */
            column-span: all;
        }
    </style>
</head>
<body>
</body>
    <!-- 父盒子
     column-count:n 控制n列
     column-rule:颜色 线条 宽度
     column-gap:间隙宽度
     column-span:all 标题横穿
 -->
    <div class="box">
        <h1>我是标题</h1>
        <div class="inner">123</div>
        <div class="inner">456</div>
        <div class="inner">789</div>
    </div>
</body>
</html>